Add GetIdCommand for retrieving features by OSM ID

[JeremyBYU]

Description of Work

Adds a new get-id CLI command for efficient OSM ID lookup using the index files generated by gol build -i. This is the CLI companion to libgeodesk PR #35, which provides the underlying getId() API.

Requires: clarisma/libgeodesk#35 (ID index support in libgeodesk)

What Changed

• New get-id command (src/gol/GetIdCommand.cpp, src/gol/GetIdCommand.h)
  • Accepts typed IDs: n123 (node), w456 (way), r789 (relation)
  • Supports multiple IDs in a single invocation
  • All standard output formats: brief, count, list, geojson, geojsonl, wkt, csv
  • Uses IdIndex::findById() for fast lookups via pre-built indexes
• Command registration in GolTool.cpp

Design Decision: Separate Command vs. Query Language Extension

The original libgeodesk PR mentioned future work to add w[id=12345] syntax to the GOQL query language. This implementation takes a different approach: a dedicated get-id command.

Why not extend the query language?

1. Semantic mismatch - GOQL filters (a[highway=primary]) conceptually select from a set. ID lookup returns exactly 0 or 1 features—it's a key lookup, not a filter.

2. Awkward composition - What does w[id=12345][highway=residential] mean? Apply both? It's redundant, the ID already uniquely identifies the feature.

3. Different mental model - Users querying by ID typically want to retrieve a known feature, not filter an unknown set. A dedicated command makes this explicit.

4. Cleaner UX - gol get-id world.gol w327189648 is direct and obvious. No need to remember filter syntax for a fundamentally different operation.

Usage Examples

# Get a single way
gol get-id world.gol w327189648

# Get multiple features
gol get-id world.gol n1 w2 r3

# Output as GeoJSON
gol get-id world.gol w123 -f geojson

# CSV with custom columns
gol get-id world.gol w123 -f csv -k id,name,highway

Open Questions

Currently if the index does not exist you will get an error like this:

❯ ./build/gol get-id $DATA_DIR/osm/planet-latest.gol w327189648 -v
 ──────  ID lookups require index files. Rebuild with: gol build -i ...

We could also fallback to brute force. But I felt that was overkill.

Finally, I would write some tests but am unsure how your testing infrastructure works.

Amount of Risk

Low risk, additive change.

• No modifications to existing query paths or command behavior
• Graceful failure if index files are missing (clear error message)
• New command is isolated and self-contained